Is it possible to set all texture nodes in a node tree to a specific vector?
Add a Reroute node with the desired value and select it. Then, you can use this script.

# First, define some stuff
# mat: the material; tree: the node tree; nodes: the node list
mat = bpy.data.materials['Material Name'] # or index
tree = mat.node_tree
nodes = tree.nodes

# We'll find the source node and store it in src
src_socket = None
if nodes.active:
  if len(nodes.active.outputs) == 1:
    src_socket = nodes.active.outputs[0]

if src_socket is not None:                       # only work if node found
  for node in nodes:                             # check each node
    if node.type.startswith('TEX'):              # only operate on textures
      for input in node.inputs:                  # check each input
        if input.type == 'VECTOR':               # only operate on vectors
          tree.links.new(src_socket, input)      # set up the link
          break                                  # only do the first vector
else:                                            # fail if no valid select
  print('No single-output node selected')


Tested on Blender v2.69 r60995.